A static, fixed inflow control device (ICD) is used in horizontal wells to control the inflow of hydrocarbons to a production line in wellbores. Horizontal wells are characterized by having an uneven drainage profile from the heel to the toe. Due to the varying pressure drops along a horizontal well, the heel of a horizontal well tends to be drained much faster than the toe. Once the reservoir surrounding the heel portion of the well has been substantially drained, water breakthrough may be experienced. Water breakthrough near the heel portion of the well will occur long before the toe portion of the well is drained, resulting in a poor total yield of hydrocarbons from the well. ICDs are arranged along the horizontal well in order to even out the drainage rate along the well in an attempt to provide a more even drainage profile along the well. The ICDs near the heel tend to have much smaller and fewer openings than the ICDs closer to the toe, thereby providing a more even drainage profile along the entire horizontal well.
An example of a static inflow control device is shown in NO 314701, which discloses a flow arrangement for use in a well through an underground reservoir. The arrangement is designed to throttle radially inflowing reservoir fluids produced through an inflow portion of the production tubing in the well. Such an arrangement is designed to effect a relatively stable and predictable fluid pressure drop at any stable fluid flow rate in the course of the production period of the well, and where said fluid pressure drop will exhibit the smallest possible degree of susceptibility to influence by differences in the viscosity and/or any changes in the viscosity of the inflowing reservoir fluids during the production period. Such a fluid pressure drop is obtained by the arrangement comprising among other things one or more short, removable and replaceable flow restrictions such as nozzle inserts, and where the individual flow restriction may be given the desired cross section of flow, through which reservoir fluids may flow and be throttled, or the flow restriction may be a sealing plug.
While static ICDs can be selected and installed with more or less correct inflow control properties at the beginning of the production life time of the well, the properties of the well will change over time in a manner that is difficult or impossible to foresee and account for when installing the ICDs during initial completing of the well. Since the ICDs are static, there is no easy way to adjust the inflow characteristics of the ICDs after the initial installment. The result is that the drainage characteristics that were correct and optimal during the first part of the production lifetime, becomes more and more off as time as the well starts to mature.
Another drawback with conventional fixed opening ICDs is that while the openings produce a pressure drop that may retard the inflow of hydrocarbons, thereby provide a more even drainage profile along the well from the toe to the heel and delaying the onset of water or gas breakthrough, the conventional ICDs have no ability to close of their openings in the event of water or gas breakthrough.
The object of the invention is therefore to provide an improved solution that solves the above problems and is more reliable in terms of functionality. These objects and others will become apparent from the following description.